Contact
Information:

In
recent years the issue of temperature management in critically ill patients, in
particular those with neurological injuries, has gained increasing attention
from the critical care community. An increasing body of evidence has shown that
the development of fever in patients with various types of neurological injury
is associated with an increased risk of adverse outcome. This has been shown most
clearly in patients with ischemic stroke, where the absolute risk of adverse
outcome (death or permanent neurological impairment) increases by 2.2% for
every degree of temperature increase. A link between fever and adverse outcome
has also been reported in patients with other types of brain injury, such as
traumatic brain injury, subarachnoid haemorrhage, and post-ischemic injury
following cardiac arrest. The fact that these associations persist after
multivariate analysis suggests that the relationship is causal, i.e. that fever
generates additional brain injury. This view is reinforced by observations from
various animal experiments, which have shown that the extent of
experimentally-induced neurological injuries increases significantly if the
animal is (externally) warmed. The risk conferred by fever appears to be
independent its cause; infectious fever, “central” (neurological) fever, and
fever occurring during reperfusion injury are all linked to increased
neurological injury.

Protectiveness
of Hypothermia

If
hyperthermia is harmful to the injured brain, it seems reasonable to assume
that perhaps hypothermia could be protective. Indeed, it is becoming
increasingly clear that induction of mild hypothermia (lowering of body
temperature to between 32°C and 34°C) in the hours following injury can be
neuroprotective, particularly in patients with post-anoxic injury. Hypothermia
can be applied in numerous clinical situations; it has been used to decrease intracranial
pressure (ICP) in patients with traumatic brain injury or ischemic stroke, to
mitigate myocardial injury following myocardial infarction, to reduce the inflammatory
response in ARDS, and in numerous other situations. However, positive effects
of hypothermia have been most convincingly demonstrated in patients with global
post-ischemic brain injury. Two multi-centred RCT’s have shown improved
outcomes associated with cooling in newborn babies with post-anoxic injury due
to perinatal asphyxia; two RCT’s have shown benefits in adult patients who
remained comatose after a witnessed cardiac arrest, who had an initial rhythm
of ventricular fibrillation (VF) or ventricular tachycardia (VT). Regarding the
latter category, the European Resuscitation Council (ERC) has recently
incorporated the use of induced hypothermia in selected patients following
cardiac arrest into the ERC guidelines for resuscitation.

In
the United States around 400,000 patients/year have a cardiac arrest; the
number in Europe is similar. Between 20% and 38% of these patients have VF or
VT as the first recorded rhythm. With appropriate emergency care around 70% of
these patients can reach the hospital alive. Thus the group of patients with a
potential indication for induced hypothermia is fairly large, particularly if
all cardiac arrests patients admitted to the ICU were to be treated with
induced hypothermia (as is the current policy in most units already using
hypothermia as a medical treatment).

Calculations
regarding the number needed to treat (NNT) to achieve one additional patient
with favourable neurologic outcome have put this number at six. This figure is
likely to be conservative, because in the abovementioned studies the time
intervals until initiation of cooling and achievement of target temperature
were relatively long (8 hours in the largest adult study, 6 hours in the neonatal
studies). The effects of hypothermia are likely to be greater if treatment is
started earlier and cooling rates are faster. However, using the NNT of 6 as a
basis for calculations, hypothermia treatment appears to be highly cost-effective
in most settings. The prices of the currently available cooling devices range
from Û10,000
to Û48,000,
roughly comparable to the price of a mechanical ventilator.

Cost-Effectiveness
of Cooling Devices

The
efficacy of the different cooling devices varies considerably; efficacy can be
judged based on the speed of cooling, ability to maintain target temperature
within a narrow range, ability to achieve slow and controlled rewarming, and
absence or low frequency of side effects. Most cooling devices use disposable
materials (surface cooling pads or intravascular catheters) to cool patients; one
device uses (partly) re-usable cooling pads. The prices for these disposable
materials range from Û90
to Û800
per patient.

However,
the cost-effectiveness of cooling devices should not be judged solely on the
basis of their purchase price and the price of the disposables. The associated
workload of the medical and nursing staff is of equal and perhaps even greater
importance. The amount and type of workload required for effective use of the
cooling devices that are commercially available varies considerably. Which device
is most appropriate and cost-effective in a specific setting will depend
strongly on that setting. In this regard, there will be considerable
differences between low-volume and high-volume ICU’s. High-volume units may
simply be large hospitals with large numbers of ICU beds, and/or units that
treat many patients with hypothermia, perhaps for different indications. Units that
use cooling devices for indications other than cardiac arrest, to treat
patients with traumatic brain injury or to control fever in patients with
neurological injuries, will usually need more than one cooling device, as these
patients usually require treatments of longer duration.

Naturally,
the costs per patient will vary considerably, and will be determined by the
factors listed above. For high-volume units a relatively expensive device, with
cheaper disposables, may be the best choice, whereas a low-volume unit may opt
for a cheaper device with more expensive disposables. Depending on the volume
of patients, the costs per patient may vary from Û1,000 per patient in a very low-volume setting to less than Û200 per patient in high-volume units. With a NNT of 6 for one
additional patient with a favourable outcome, without an increase in the length
of stay, it becomes clear that hypothermia is indeed one of the most
cost-effective treatments currently available in intensive care. Even when using
the price at the top end of the range above (Û1,000 per patient) to calculate the overall costs, this would
require an investment of Û6,000
to save one patient; the price per quality-adjusted life-year would still be
less than Û900.
This compares highly favourably with many routine interventions in the critical
care setting. As the actual price per patient will be significantly lower in most
settings, cooling devices will be a worthwhile investment.

No comment

Highlighted Products

The HAMILTON-C3 ventilator is a modular high-end ventilation solution for all patient groups. Offering a number of unique features, the HAMILTON-C3 is one of the first ventilators featuring the “Ventilation Autopilot” INTELLiVENT-ASV®. The HAMILTON-C3’s...

Based on the long-established and reliable OTF/AS cryostat, the new OTF5000 brings the extensive range of Bright cryostats completely up to date.
New styling coupled with improved user ergonomics, the latest blade systems in the ever-reliable and powerful...

The fully featured ICU ventilator, HAMILTON-MR1, guarantees uncompromised continuous ventilation care from the ICU to the MRI scanner and back. Its reliability and high performance, with advanced lung-protective strategies and patient-adaptive modes,...

The HAMILTON-T1 combines for the first time the functionality of a fully featured intensive care unit ventilator with the compactness and ruggedness required for transport. This is why the HAMILTON-T1 enables you to provide optimal ventilation therapy...